1. Field of the Invention
The present invention relates to an information processing apparatus and method, and more particularly to an information processing apparatus and method capable of properly receiving and transmitting, e.g., a copyright content.
2. Description of Related Art
With the recent spread of public wide area networks (hereinafter called WAN) typically the Internet and local area networks (hereinafter called LAN) installed in general houses, various data communications are vigorously performed via these networks.
When a content such as video and music is transferred via a network, authentication and key exchange are performed between a communication partner apparatus and an encrypted content is transmitted in order to protect copyright (refer to a non-patent document DTCP Specification Volume 1 Version 1.3 (Information Version).
From the viewpoint of the copyright, there is a case in which although copy and transmission in a home are permitted, content transmission to and from another home interconnected by WAN is desired to be limited. For example, this limitation becomes necessary in a case in which although a content obtained by recording television broadcasting can be used in a private use range (in a home), transmission of this content to the third party is considered infringement of the copyright.
Under this limitation, an apparatus (transmission apparatus) for transmitting a content protected by the copyright is required to determine whether a communication partner apparatus (reception apparatus) for receiving the content is in the same LAN or is connected via a WAN.
For example, it is possible to check from an IP address whether a communication partner is in the same subnet, or to know from the number of routers (Hop Count) through which an IP communication packet has passed whether a communication partner is connected via a WAN (the Internet). In communications via a WAN (the Internet), however, the same subnet connection without IP routers becomes possible if technologies such as a virtual private network (VPN) are used. Namely, it is possible to obtain contents illegally.
A method has been proposed which determines a communication distance by measuring a round trip time (RTT) of communications with a communication partner. This utilizes that a WAN such as the Internet has a longer communication data transmission time than that of a home LAN, because of a longer communication distance and a time required for processes at intermediate routers and the like.
For example, as shown in FIG. 1A, a transmission apparatus measures a round trip time such as a transmission time of a measurement command (S1) taken to reach a reception apparatus and a transmission time of a response (S2) to the measurement command from the reception apparatus. A round trip time in the same home network is a predetermined specified time (e.g., 5 mS) or shorter, whereas communications via the Internet (WAN) take a longer time (e.g., 7 mS). It is therefore possible to determine from the round trip time whether the reception apparatus is connected via a WAN.